1. Field of the Invention
This invention relates to a radiographic intensifying screen and a process for the preparation of the same. More particularly, this invention relates to a radiographic intensifying screen comprising a support a phosphor-containing resin layer provided thereon in which a resinous binder and a phosphor are contained in a weight ratio of 1 : 1 to 1 : 100, and a process for the preparation of the same.
2. Description of Prior Arts
In a variety of radiographic processes such as medical radiography for diagnosis and industrial radiography for nondestructive inspection, a radiographic intensifying screen is employed in close contact with one or both surfaces of a radiographic film such as an X-ray film for enhancing the radiographic speed of the system. The radiographic intensifying screen consists essentially of a support and a phosphor-containing resin layer provided thereon. Further, a transparent film is generally provided on the free surface of the phosphor-containing resin layer to keep the layer from chemical and physical deterioration.
The phosphor-containing resin layer comprises a resinous binder and phosphor particles dispersed therein. The phosphor-containing resin layer is generally provided on a support under an atmospheric pressure utilizing the following coating procedure.
The phosphor particles and the resinous binder are mixed in an appropriate solvent to prepare a coating dispersion. The coating dispersion is directly applied onto a surface of a support for a radiographic intensifying screen under an atmospheric pressure using a doctor blade, roll coater, knife coater or the like, and the solvent contained in the coating dispersion applied is removed to form a phosphor-containing resin layer. Alternatively, the phosphor-containing resin layer is provided on the support by applying the coating dispersion onto a false support such as a glass plate under an atmospheric pressure, removing the solvent from the coating dispersion to form a phosphor-containing resin film, peeling off the film from the false support, and then causing the film to adhere to the genuine support.
When excited with a radiation such as X-rays passing through an object, the phosphor particles contained in the phosphor-containing resin layer emit light of high luminance in proportion to the dose of the radiation. Accordingly, an X-ray film placed in close contact with the phosphor-containing resin layer can be exposed sufficiently to form a radiation image of the object, even if the radiation is applied to the object at a relatively small dose.
It is desired for the radiographic intensifying screen having the above-mentioned basic structure to exhibit a high radiographic speed and to provide an image of high quality (high sharpness and high graininess). In particular, from the viewpoint of obtaining more accurate and detailed information of an object, it is desired to develop a radiographic intensifying screen which provides an image of improved sharpness.